Pack animals such as pack horses, mules, donkeys, and others support cargo on pack "saddles" designed specifically to enable mounting and balancing of the cargo on the animal. The cargo is typically secured to the pack saddle by pack lines that lash the cargo to the pack frame in a tight, balanced load.
Possibly the most used form of pack saddle, at least for horses, mules and donkeys, is the "Decker" saddle. This form of pack saddle is a simple construction, including a pliable pad "half breed" and cover that is mounted by appropriate straps to the animal's back. A pair of "D" rings project upwardly from the saddle directly over the animal's spine. The rings are used as a tie-off base for the pack lines to secure the cargo to the saddle and pack animal.
Tying and balancing cargo on a pack animal is nearly an art form, requiring long experience and training to do properly. One problem is holding the cargo in place while the pack lines are lashed to the saddle, and positioning the pack lines so the cargo will not shift and eventually fall from the pack.
As a solution, rigid self-contained canisters have been provided that can be attached by straps to pack saddle "D" rings. While this solution is serviceable for some cargo, the space provided within the canisters is limited and will not work at all for some loads-fence posts being one example.
Another solution is provided by manufacturers of large canvas or leather "saddle bag" packs that also function to hold cargo. These packs are connected together by a web which fits over the animal's back and does not require a pack saddle for attachment. However, saddle bag type carriers also suffer similar cargo size and shape limitations as the rigid canisters mentioned above.
A shelf mounted to a pack saddle was designed and used experimentally by the present applicant. However serious drawbacks were experienced. While the rigid shelf offered stability to a wider variety of cargo, problems arose both in use and in storage due to rigid frame configuration. Also the shelf structures when not in use, present an unnecessary hazard, projecting rigidly outward from the pack animal and constantly catching on passing branches, tree trunks, etc.
U.S. Pat. No. 618,329 to Calvert offers a solution to the above problem by providing a folding "Luggage Carrier for Pack Animals". Here, a hinge was provided between vertical and horizontal carrier frame (shelf) members, allowing the shelf to fold against the vertical member when not in use. However the structure also requires the use of "brace bars" that support the shelf from the vertical member. The bars are situated at opposed ends of the shelf and therefore present an obstruction to any load that is longer than the dimension between the shelf ends. Thus much of the advantage of the folding frame is lost in the disadvantage of limited utility.
The hinges in the Calvert device are located directly adjacent the animal where weight of the cargo presses the frames into the animal's sides. The segments of the hinges are thus situated closely adjacent to the animal's hide. While in use, the hinge members can pivot slightly, pinching, pulling hairs and causing discomfort to the animal.
A need has therefor remained for a pack frame that will provide the support advantages of a shelf, without cargo length limitations, and that may be collapsed for storage on or off the pack animal without causing discomfort to the animal. The present invention fills this need, as will be fully understood below.